title: Room temperature thermotropic liquid crystalline phases of catanionic surfactants derived from quaternary ammonium surfactants and bis(2-ethylhexyl)sulfosuccinate.
abstract: OBJECTIVE
  Properties of catanionic surfactants can be tailored by the choice of appropriate headgroups and hydrocarbon tails. Thermal behavior of catanionic surfactants can be influenced by the length and number of alkyl chains.
  
  
  METHODS
  A series of eight catanionic surfactants were synthesized from quaternary ammonium surfactants as the cationic counterpart and bis(2-ethylhexyl)sulfosuccinate (AOT) as the anionic counterpart. The thermal properties and the liquid crystalline properties of these catanionic surfactants were studied by the following methods: Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Hot-Stage Polarized Light Microscopy (HSPLM), and X-ray Diffraction (XRD).
  
  
  RESULTS
  The results indicate that transition temperatures, enthalpies of transition, and mesophase structures vary with the length and number of chains attached to the quaternary nitrogen. These compounds exhibit room temperature liquid crystalline (LC) textures that are predominantly "fan-like," as observed by HSPLM, and phases that are hexagonal columnar, as observed by XRD, with the exception of one compound which exists as a nematic liquid crystal at 25°C. Additionally, all of the surfactants also exhibit thermal stability in the range of 256-300°C.
authors.affiliation: Department of Natural Sciences, University of Houston-Downtown, One Main Street, Houston, TX 77002-1001, USA. Electronic address: Joser@uhd.edu.
authors.forename: Robin
authors.initials: R
authors.lastname: Jose
authors.forename: Tilesh Jayantilal
authors.initials: TJ
authors.lastname: Patel
authors.forename: Troy Allen
authors.initials: TA
authors.lastname: Cather
authors.forename: Janusz
authors.initials: J
authors.lastname: Grebowicz
authors.forename: Haesook
authors.initials: H
authors.lastname: Han
authors.forename: Pradip Kumar
authors.initials: PK
authors.lastname: Bhowmik
authors.forename: Dena Mae
authors.initials: DM
authors.lastname: Agra-Kooijman
authors.forename: Satyendra
authors.initials: S
authors.lastname: Kumar
keywords: AOT; APS; Advanced Photon Source; Amphiphilic liquid crystal; Catanionic surfactant; DSC; Differential Scanning Calorimetry; HSPLM; Hot-Stage Polarized Light Microscopy; Ion-pair amphiphile; LC; Mesophase structure; RT; Room temperature liquid crystal; T(i); TGA; Thermal Gravimetric Analysis; X-ray Diffraction; XRD; bis(2-ethylhexyl)sulfosuccinate; enthalpy of isotropization; entropy of isotropization; liquid crystalline; room temperature; temperature of isotropization; total enthalpy in the observed temperature range; total entropy in the observed temperature range; ΔH(i); ΔH(ovr); ΔS(i); ΔS(ovr)